Causes of Diarrhoea

Diarrhoea usually occurs when fluid cannot be absorbed from your bowel contents, or when extra fluid is secreted into the bowel, causing watery faeces.

Conditions causing short-term diarrhoea:


Diarrhoea is usually a symptom of gastroenteritis, an infection of the bowel and can be result from:

  • Bacteria,  (E. coli), salmonella and shigella – these may all cause food poisoning 
  • Parasites 
  • A virus, such as norovirus or rotavirus.  Rotaviruses infect the stomach and  intestines (bowel) of children and can spread from child to child. 

Travellers’ diarrhoea

Diarrhoea caused by contaminated food or water from a foreign country is known as travellors’ diarrhoea

Other short-term causes of diarrhoea include:
• Emotional upset or anxiety
• Drinking too much alcohol
• Drinking too much much coffee
• A food allergy


Diarrhoea can also be a side effect of taking medicines including:
• Antibiotics
• Antacid medicines that contain magnesium
• Some medicines used in chemotherapy
• Non-steroidal anti-inflammatory drugs
• Selective serotonin reuptake inhibitors
• Statins (cholesterol-lowering medicines)
• Laxatives – which can help relieve the symtoms of constitpation

The patient information leaflet that comes with your medicine should state whether diarrhoea is a possible side effect.